1. Field of the Invention
The present invention relates to a method for manufacturing a plugged honeycomb structure, and more specifically to a method for manufacturing a plugged honeycomb structure, the method being capable of inhibiting depression and protrusion of the plugging portion.
1. Description of Related Art
In various fields such as chemistry, electric power, and iron and steel, there is employed a ceramic plugged honeycomb structure excellent in thermal resistance and corrosion resistance as a carrier for a catalyst device or as a filter for an environmental measure, collection of a specific substance, or the like. In particular, recently, a plugged honeycomb structure has been highly demanded as a diesel particulate filter (DPF) for trapping particulate matter (PM) discharged from a diesel engine.
As shown in FIG. 8, the plugged honeycomb structure 31 is a structure where plugging portions 36 are formed in an end portion of each of the cells 34 of the honeycomb structural portion 33 provided with porous partition walls 32 separating and forming the cells 34 functioning as fluid passages. FIG. 8 is a cross-sectional view cut along a plane including the central axis, schematically showing a structure of a plugged honeycomb structure. The plugging portions 36 are disposed in one open end of each of the predetermined cells 34 and in the other open end of each of the remaining cells 34. In the plugged honeycomb structure 31, plugging portions 36 are alternately formed in open ends of cells 34 in the fluid inlet face B and open ends of cells 34 in the fluid outlet face C (see, e.g., Patent Document 1).
For example, when the plugged honeycomb structure 31 is used as a DPF to introduce a target gas G1 to be treated into cells 34 from the inlet face B, the gas G1 passes through the porous partition walls 32, flows into the adjacent cells 34, and is discharged from the outlet face C as treated gas G2. When the target gas G1 passes through the partition walls 32, dust and particulate matter contained in the target gas G1 are trapped by the partition walls 32.
The plugged honeycomb structure 31 described above can be manufactured by the plugging step after obtaining a columnar honeycomb formed body having porous partition walls separating and forming a plurality of cells functioning as fluid passages. In the plugging step, in the first place, a mask is bonded to one end face of the honeycomb formed body. The mask is bonded by applying an adhesive film on one end face of the honeycomb formed body and making holes in the adhesive film at portions corresponding to the cells to be plugged by laser processing with image processing. Then, the one end face having the mask of the honeycomb formed body is immersed in slurried plugging material (plugging slurry) containing ceramic and stored in a container to fill the plugging material into the cells where plugging portions are to be formed. Also, in the other end face of the honeycomb formed body, the plugging material is filled into the cells where plugging portions are to be formed in the same manner.